How can I have someone see my tweet if they are not following me?(e.g. celebrity)?

Well I see how some people tweet to celebrities or people and the people actually dm you or RT it. If this happened to you, what did you do? I realised that the people I follow dont get my tweets, or do they?How do they get them? I reply to them like @??? and then the tweet, so will that get to them... Lol please share!